470 SUPPLEMENT. 



SERTULARIA PINNASTER After assuring myself that S. pinnaster 

 had been founded upon an unripe specimen of S. fallax, I com- 

 menced the examination of the S. rosacea from the same 

 locality and from which the above descriptions of the vesicle 

 were made, but there was another bunch from the rocky bottom 

 of Stronza Firth, Orkney Isds., found growing upon Delesseria 

 sanguinea which I cannot believe to be the same species. There 

 is no difference between this and S. rosacea in the habit of the 

 polypidom, nor in the structure or shape of the cells, but the 

 ovaries are totally distinct. (Notwithstanding the differences in 

 the ovarian vesicle, I consider these specimens as belonging to 

 S. rosacea. G. J.) 



SERTULARIA TAMARISCA ) In April 1845, a small polypidom came 

 SERTULARIA MARGARETA J up off Huntly Fort, without vesicles, 

 which I did not hesitate (by the help of your first edition) to 

 call S. tamarisca. In June 1846, a fortunate haul off Bu- 

 channess brought up four fine specimens in full blow. Intending 

 to examine them beneath the microscope, they were placed with 

 the rest in a bucket of sea-water, but bad weather coming on, 

 I was glad to secure them by putting one into a phial of 

 Goadby, and the rest were dried under pressure. On my return 

 home I procured your second edition, and commenced the arrange- 

 ment of the Zoophytes. When the bottle specimen is examined 

 the vesicles are seen to be crowned with spines, and it is named 

 S. Margarita. Wishing to trace the development of the vesicle 

 in the species, the others procured at the same time and upon 

 the same attachment were soaked in water, when every vesicle 

 presented the character of S. tamarisca. Are these different 

 species 1 or is the shape of the vesicle of no specific value 1 

 These are the characters of S. tamarisca and of that of the crown 

 of spines. Polypidom erect, pinnate, sparingly branched ; Cells 

 opposite, tubular, upper half divergent and free, aperture 

 tri-crenate, the crenations filled up by a triangular flexible 

 membrane, the edges uniting when the animal retires to form 

 an operculum. So far the two species are identical. Ovary 

 (of one of the specimens) arising from a short stalk, thence 

 gradually increasing for half its length. The upper part is 

 crowned by laminar spines diverging in three rows from the 

 centre the exterior spine is bifid. 



SERTULARIA FUSCA quite young in March 1846, in thirty-five f. off 

 Staples. Generally attached to stones. Many old fronds off 



